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Bureau of Mines Information Circular/1985 



Analysis of Dredge Safety Hazards 



By Stephen A. Swan 




UNITED STATES DEPARTMENT OF THE INTERIOR 



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Mines 75th an^ 



Information Circular 9008 



Analysis of Dredge Safety Hazards 



By Stephen A. Swan 




UNITED STATES DEPARTMENT OF THE INTERIOR 

Donald Paul Hodel, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 




Library of Congress Cataloging in Publication Data: 



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Swan, Stephen A 

Analysis of dredge safety hazards. 

(Information circular /Bureau of Mines ; 9008) 

Includes bibliographic references. 

Supt. of Docs, no.: I 28.27:9008. 

1. Dredges— Safety measures. I. Title. II. Series: Information cir- 
cular (United States. Bureau of Mines) ; 9008. 



TN295.U4 [TN345] 622s [622\32'0289] 84-600309 



/H 



CONTENTS 

Page 



1^ 



Abstract 1 

Introduction 2 

Dredge fatalities 2 

Dredge operations 3 

General hazards analysis 3 

Pipeline hazards 6 

Railing hazards 6 

Ladder hazards 7 

Electrical hazards 10 

Wire rope hazards 10 

Fire hazards 11 

Personal flotation device 11 

Conclusions 14 

ILLUSTRATIONS 

1 . Single workboat 4 

2. Pipeline without walkway 4 

3 . Safe walkway 5 

4. Walkway safety hazard 5 

5. Power cable along pipeline 6 

6. Well-maintained railing 7 

7. No railings 7 

8 . Dragline pinch point 8 

9. Ladder or stairway 8 

10. Poorly constructed ladder 9 

11. Unsafe ladder 9 

12. Power cable 10 

13. Fire hazard 12 

14. Failure to wear personal flotation devices 13 

15. Improper storage of personal flotation devices 13 

16. Abuse of personal flotation devices 14 

TABLES 

1. Mining dredge fatalities, January 1973-June 1983 3 

2 . Location of dredges included in hazard analysis 3 





UNIT OF 


MEASURE 


ABBREVIATIONS 


USED 


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ft 


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year 


pet 


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ANALYSIS OF DREDGE SAFETY HAZARDS 

By Stephen A. Swan 



ABSTRACT 

Bureau of Mines research has not included analyses of mining dredge 
safety since 1948. Because of the increasing use of dredges, 63 fatal 
accidents and several hundred nonfatal injury accidents involving dredg- 
es were examined. Also, 31 working dredges and 3 dredge manufacturers 
were visited to acquire qualitative information. 

Drowning accidents represented 59 pet of the fatalities and are delin- 
eated in detail. Also, countermeasures against other hazards are 
discussed. 



1 Mining engineer, Twin Cities Research Center, Bureau of Mines, Minneapolis, MN, 



INTRODUCTION 



The Bureau of Mines concern about min- 
ing dredge safety is longstanding. S. B. 
Ash studied safety practices related to 
California gold in the early 1930' s. 2 In 
the 1940 's, R. W. Fatzinger visited hy- 
draulic and dredge mining operations in 
Alaska and California. He also reviewed 
10 yr of accident data pertinent to such 
mining in the United States. The data, 
covering the period 1933 to 1942, includ- 
ed those related to 36 fatalities and 
3,700 injuries in dredge mining. 3 

It is generally assumed that dredge op- 
erations are "safe" — certainly much safer 
than other mining and construction opera- 
tions to which they are usually compared. 
It is true that personal injury rates 
for dredge workers, normalized in terms 
of worker-hours, dredge operating hours, 
or tons of material moved, are lower than 
those for many other mining operations. 4 
Still, over the 10-1/2-yr period that 
ended in June 1983 63 people were killed 
and almost a thousand injured in mining 
dredge operations in the United States. 



The research discussed here included 
field visits to a selected sample of min- 
ing dredge operations, an examination of 
dredge-related injury data in the files 
of the Mine Safety and Health Administra- 
tion's Health and Safety Analysis Center 
in Denver, and field visits to a selected 
number of nonmining dredge operations. 
In all, field visits were made to 31 
dredge operations. Three companies whose 
principal business is the manufacture of 
dredges and dredge components were also 
visited. Design considerations for safe- 
ty were discussed, as were training and 
product liability questions and the acci- 
dent experience of company field repre- 
sentatives during erection, initial oper- 
ations, and maintenance of delivered 
dredges. 

The information was analyzed in five 
separate categories which appear to be 
the most important in terms of developing 
countermeasures for these accidents. 
These categories include drowning, slips 
and falls, electrical, mechanical, and 
fire. 



DREDGE FATALITIES 



To try to quantify 
were taken from the 
Health Administration's 
since January 1973. 
fatal accidents that 
mining dredges during 
people (average) died 
was also an annual ave 
95 nonfatal injury acci 



the hazards , data 
Mine Safety and 
accident records 
Table 1 shows the 
occurred on U.S. 
those years. Six 
each year. There 
rage of more than 
dents, as well as 



2 Ash, S. H. Safety Practices in Cali- 
fornia Gold Dredging. BuMines B 352, 
1932, 31 pp. 

■^Fatzinger, R. W. Safety Practices in 
Dredging and Hydraulic Mining. BuMines B 
450, 1948, 76 pp. 

^Mine Safety and Health Administration. 
Annual and Quarterly Injury Reports. 



several hundred noninjury accidents. 
Note that about 59 pet of the fatalities 
in the table are drowning accidents. 
There were more drownings from boats and 
walkways (mostly pipeline walkways) than 
from the dredges themselves. Machinery 
accounted for a smaller number. An ex- 
ample of such an accident is one in which 
a worker was repairing a dredge-to-shore 
conveyor belt. The belt was started 
while he was working on it, and he was 
knocked into the water. Five of the fa- 
tal accidents were from electrocutions. 
Twenty-one fatalities involved shore- or 
dredge-based support equipment, including 
a rollover of a front-end loader, a fall- 
ing crane boom, a fall into a hopper, and 
conveyor accidents on land. 



DREDGE OPERATIONS 



The majority of the dredges visited 
were extracting sand or gravel. Others 
in the sample included units engaged in 
recovering phosphate, gold, ilmenite, and 
coal. Dredges involved in land reclama- 
tion after mining and settling pond 
maintenance — for example, in recreational 
area development, specifically units en- 
gaged in making lakes for fishing and 
water sports — were also included in the 
analysis. 



Of the 31 dredges visited, 18 were 
built by manufacturing firms whose prin- 
cipal business is the design and manufac- 
ture of dredges. Thirteen units were 
built by the owners or by local machine 
shops not primarily engaged in dredge de- 
sign and construction. The 31 dredge op- 
erations included in this analysis were 
located in 10 States (table 2). Three of 
the four Alaskan dredges were mining 
gold. 



TABLE 1. - Mining dredge fatalities, 
January 1973- June 1983 

Total 



Drowning: 

Boat 

Dredge 

Walkway 

Machinery 

Other 

Total 

Electrocution (shore or 

dredge) 

Mobile machinery (shore). 
Fixed machinery (shore or 

dredge) 

Total 



TABLE 2. - Location of dredges included 
in hazard analysis 

Sites 



fatalities 
11 




visited 
4 


10 




1 


6 




6 


5 




1 


5 




4 








37 


4 






2 


5 


Ohio 


5 


8 




3 






1 








13 





63 



GENERAL HAZARDS ANALYSIS 



Many dredges depend upon a workboat to 
transport personnel and materials between 
the dredge and shore (fig. 1). It is im- 
portant to note that most of the dredge 
operations that depend upon a boat had 
only one such boat. Several fatal acci- 
dents might have been avoided had a sec- 
ond boat been immediately available to 
enable persons who might have rendered 
aid to get to the dredge quickly. In 
these accidents the only available boat 
was tied up at the dredge, and the victim 
was the only person on the dredge. 

Some dredges have workboats but do not 
depend upon them to transport people be- 
tween dredge and shore as a normal prac- 
tice. The crew moves between the dredge 



and shore by walking the pipeline. Fig- 
ure 2 is an example of such a pipeline. 
Several dredgemasters reported that they 
had "knocked a guy off the pipeline" when 
they started the pumps. If access be- 
tween the shore and the dredge depends 
primarily upon walking the pipeline, it 
follows that a safe walkway must be pro- 
vided. Figure 3 shows a safe walkway 
separated from the pipeline. Infrequent- 
ly, however, the design of the walkway is 
such that there are large gaps between 
one section and another (fig. 4). In ad- 
verse weather negotiating a gap of this 
size can be particularly difficult and 
hazardous undertaking for the dredge 
worker. 




FIGURE 1. - Single workboat. 




FIGURE 2. - Pipeline without walkway. 




FIGURE 3. - Safe walkway. 




FIGURE 4. - Walkway safety hazard. 



PIPELINE HAZARDS 



A more specific hazard associated with 
pipelines is related to moving the line 
and making repairs where the job of mak- 
ing connections between sections involves 
the danger of crushing or pinching injur- 
ies. Although several dredges provided 
work platforms on the pipeline buoyancy 
structures, many do all the work from 
workboats, sometimes using people who 
have little skill in boat operation or 
safe mooring. 



Another hazard area related to the 
pipeline involves power cables carried 
along the pipeline. One obviously un- 
satisfactory arrangement is shown in fig- 
ure 5. If the insulators that carry the 
line are inadequate, or if the line 
droops into the water, chances of break- 
ing or electrical shorts are greatly 
increased 



RAILING HAZARDS 



As on the pipeline walkways, railings 
make an important safety contribution on 
dredge decks. Many dredges had strong, 
well-maintained deck railings (fig. 6). 
Some, however, had no railings at all 
(fig. 7). A need for guardrails inboard 
was evident on the type of dredge that 



mounts a dragline in a deck well. Two of 
the dredges visited had arrangements sim- 
ilar to that show in figure 8. Note that 
as the dragline swings , a pinch point is 
created between the cab and the deck. 
Several accidents have occurred when 
maintenance people were not aware of this 





FIGURE 5. • Power cable along pipeline. 




V 



FIGURE 6. • Well-maintained railing. 




FIGURE 7.- No railings. 



potential hazard. The problem is not one 
of having maintenance done during drag- 
line operations, because most companies 
require that the dragline be stopped 



during maintenance. The accidents that 
have occurred involved people doing deck- 
work and inadvertently stepping into the 
well. 



LADDER HAZARDS 



Figure 9 is an example of a ladder (or 
stairway) into a lower hull area of an 
otherwise well-constructed dredge. Note 
the absence of handrails. Tripping and 
bumping hazards are also visible in the 
stairwell area. 

Ladders for abovedeck maintenance are 
frequently designed with little thought 
about the safety of their use. Figure 10 
shows such a ladder, made of round stock 
welded to an I-beam. The spacing is in- 



appropriate, the toe room is inadequate, 
and the footing is poor. Often it was 
not a cost problem that led to poor lad- 
ders, but simply lack of attention to the 
details of safety design. Figure 11 
shows another ladder welded to an A- 
frame. The rungs are not evenly placed, 
and the ladder is quite difficult to ne- 
gotiate. Some of the lower rungs have 
been removed because they constituted an- 
other hazard to people working near the 
base of the A-frame. 




FIGURE 8. • Dragline pinch point. 




\ 



FIGURE 9. - Ladder or stairway. 





FIGURE 10. - Poorly constructed ladder. 




FIGURE 11. - Unsafe ladder. 



10 



ELECTRICAL HAZARDS 



Electrical hazards are common on many 
smaller dredges. Figure 12 shows poor 
handling of a power cable. Even on larg- 
er dredges, electrical safety is some- 
times given inadequate attention. Dis- 
tribution boxes are poorly placed and im- 



properly mounted. Cables are routed with 
little regard for insulation protection, 
not to mention the trippling hazards cre- 
ated. Common safety practice must be 
followed. 



WIRE ROPE HAZARDS 



Wire rope breakage on dredges is not 
uncommon. Both broken positioning lines 
and broken digging ladder control lines 
were observed during field visits. On 
one occasion, the end of a snapped rope 
violently struck and entered the opera- 
tor's compartment. It would undoubtedly 
have injured the dredgemaster had he been 
in his usual position at the time. There 
are several countermeasures. One is the 



proper handling of the equipment so that 
the rope is not overloaded. Another is 
regular inspection and replacement of 
work or damaged rope. A third is more 
careful design to ensure that the rope 
size is appropriate to the loads experi- 
enced during the majority of the opera- 
tions. Finally, proper guarding of the 
cables and drums can be invaluable to en- 
sure that a broken cable does not injure 




FIGURE 12. - Power cable. 



a worker. Although some of the ropes and 
sheaves observed during the study were 
well guarded, most were not. Many drums, 



11 



including drums immediately adjacent to 
the operator's compartment, were not 
guarded. 



FIRE HAZARDS 



Fires on dredges do not appear to be a 
common occurrence, but when one did 
occur, the results were frequently ex- 
tremely expensive and dangerous. In most 
of the operations visited, the fire pro- 
tection practices appeared to be substan- 
tially less well developed than those in 
shore-based plants. Scenes like that 
shown in figure 13 were very common. 



Flammable debris (oily rags, cartons, and 
fluids) were frequently observed in areas 
where ignition was possible. The train- 
ing given to most dredge workers relative 
to fire prevention and fire suppression 
was minimal. The available fire suppres- 
sion equipment was not always easily ac- 
cessible and properly maintained. 



PERSONAL FLOTATION DEVICE 



Perhaps the single greatest hazard on 
dredges is related to the simple fact 
that work is done over water. Only one 
of the 31 dredges vistied required water 
survival training and demonstrated water 
survival proficiency as conditions of em- 
ployment. All except two of the dredge 
operations required the wearing of a per- 
sonal flotation device (PFD) , according 
to the written safety rules of each com- 
pany. However, in only a few cases was 
the wearing of PFD's observed to be 
enforced. 

In the majority of operations visited, 
no one was wearing his PFD. Scenes like 
that depicted in figure 14 were common. 
On some of the very smallest and oldest 
dredges it was apparent that the avail- 
able PFD's were never worn. On some of 
the largest it was not uncommon to find 



PFD's stored as in figure 15, not well- 
maintained, not inspected, not fitted, 
and not assigned to individuals. Some- 
times the PFD's, even new ones, were ly- 
ing in dirt and grease as shown in figure 
16. 

A few of the dredges had the PFD's as- 
signed to individuals; these PFD's were 
well maintained and regularly inspected 
and were worn while working over water at 
all times except when the person was in- 
side the dredge control house. However, 
at most operations the dredge workers 
complained that the PFD was uncomfort- 
able, too old to be of any use, or a work 
hazard because it tended to catch on 
things. In short, a multitude of reasons 
were offered in defense of not wearing a 
PFD. 



12 




FIGURE 13. - Fire hazard. 



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FIGURE 14. - Failure to wear personal flotation devices. 




FIGURE 15 - Improper storage of personal flotation devices. 



14 




FIGURE 16. • Abuse of personal flotation devices. 
CONCLUSIONS 



More attention needs to be given to 
published safety requirements, including 
those in American National Standards In- 
stitute Standard A10.15 and in the Code 
of Federal Regulations. The three dredge 
manufacturers visited appeared to have 
studied and considered the standards in 
terms of design improvements. Beyond 



that, all three expressed the general 
view that safety is the responsibility of 
the operator, not the manufacturer. Con- 
siderable interest was expressed in ob- 
taining information about effective safe- 
ty practices, including the development 
of safe job procedures, at many of the 
operations visited. 



£U.S. GPO: 1985-505-019/20,009 



INT.-BU.OF MINES, PGH..P A. 27890 



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